Tubuliporina

Grischenko, Andrei V., Gordon, Dennis P. & Melnik, Viacheslav P., 2018, Bryozoa (Cyclostomata and Ctenostomata) from polymetallic nodules in the Russian exploration area, Clarion - Clipperton Fracture Zone, eastern Pacific Ocean-taxon novelty and implications of mining, Zootaxa 4484 (1), pp. 1-91 : 19-20

Tubuliporina sp. incertae sedis

( Figs 2F , 9 )

Material examined. Specimen ZIRAS 1/50674, colony detached from nodule, YMG R.V. Yuzhmorgeologiya cruise YMG18–01, Stn 7, 18 July 2003, 13.44816° N, 129.15189° W, 4673 m. One specimen only.

Description. Colony erect, white, comprising only five autozooidal peristomes and one peristome of smaller diameter ( Fig. 9A–D ). Three successive autozooids in lower part of colony comprising proximal axial part and distal peristomial part projecting at c. 45° from axis, each zooid budding from one below it in roughly same plane. From axil of second and third zooids in series arise two additional autozooids, with peristomes directed distally, and a third zooid, with short small peristome ( Fig. 9E–H ), opening outward from midlength of the two autozooids, just distal to transverse ridge that may represent a former fracture ( Fig. 9I, J ).

All zooids with irregularly concentric ridges and furrows; between these, crystallites aligned in parallel vertical arrays; small simple pseudopores sparse. Peristomial rims thin, more or less circular ( Fig. 9K ). Inner surface of peristomes with skeletal microstructure of distally imbricated triangular crystallites.

Definite gonozooid not in evidence; dimorphic zooid bearing small-diameter peristome may represent simple female gonozooid.

Ancestrula lacking; colony broken at base.

Measurements (mm). Specimen ZIRAS 1/50674 ( Fig. 9 ): Colony height 2.72, width 1.39; ZL 0.850–1.303 (1.049 ± 0.180) (n = 5); PeL 0.353–0.888 (0.619 ± 0.191) (n = 5); PeD 0.210–0.238 (0.229 ± 0.011) (n = 5); ApD 0.174–0.232 (0.214 ± 0.023) (n = 5). Sole female(?) (n = 1): ZL 0.953; PeL 0.213; PeD 0.128; ApD 0.122.

Remarks. More specimens are needed to determine the full suite of morphological characters present in this species. The small peristome present in one zooid raises the possibility that it represents a simple 'dwarf' gonozooid. Although its opening is just distal to what might represent a fracture, and hence an instance of repair, normal reparative processes should typically result in a peristome of near-normal diameter, not a peristome about half the usual size. Insofar as two rectangulate CCZ species have what appear to be simple gonozooids instead of much-larger incubation chambers (see below under Anyutidae n. fam.), it is possible that the small-diameter peristome in this indeterminate tubuliporine might represent an oeciostome. If this is the case, then this taxon certainly represents a new genus and probably a new family. Mediating against the gonozooid interpretation is a lack of increased pseudopore density.

Distribution. Recorded from a single station with coordinates 13.44816° N, 129.15189° W, at 4673 m depth.

Figures

FIGURE 2. Colonies of some cyclostome bryozoans, in vivo, attached to polymetallic nodules. A–E, Pandanipora helix n. gen., n. sp.: A, specimen GLD4–09, Stn 190; B, specimen GLD4–12, Stn 262; C, specimen YMG4–07, Stn 143; D, specimen YMG4–13, Stn 295; E, specimen GLD 4–11, Stn 212. F, Tubuliporina sp. indet., specimen YMG18–01, Stn 7. G, H, Abyssoecia elevata n. gen., n. sp.: G, specimen GLD4–09, Stn 196; H, specimen GLD4–09, Stn 191. I, Discantenna metallica n. sp.: specimen GLD4–11, Stn 224. J, K, Frontohornera frontalis n. gen., n. sp.: J, specimen YMG4–07, Stn 124; K, specimen GLD4–11, Stn 210. L, Alyonushka hystricosa n. gen., n. sp.: specimen GLD4–09, Stn 199. M, Calyssopora volcano n. gen., n. sp.: specimen YMG18–01, Stn 33. N, O, Anyuta anastema n. gen., n. sp.: N, specimen GLD4–09, Stn 180; O, specimen YMG4–06, Stn 71. Scale bars: 1 mm.

FIGURE 9. Tubuliporina sp. incertae sedis. Specimen ZIRAS 1/50674. A–C, rotational and D, tilted, views of sole colony; E–H, rotational views of distal part of colony showing two autozooidal peristomes and a smaller-diameter (?female) peristome; I, J, close-ups of smaller peristome; K, close-up of right-hand peristomial aperture in D. Scale bars: A–D, 250 µm; E–H, 200 µm; I–K, 100 µm.